m240b or m60 if you want to hold down your enemies or keep them busy while letting your teammates accomplish the goal. but as said there isn't an effect this has on enemies or any bonuses that come from it

Better way to surpress them is damaging them if over medium-long distance: forcing them to alternate routes, take cover, distract them trying to find you, or in some cases, even kill and respawn. Players are very wary when they are damaged This kind of damage surpress works with any weapon, you just need to aim well, and hit anything you see moving towards your objectives.